1. Technical Field
This invention relates to tubular linear motors, and more specifically to winding arrangements for tubular linear motor primaries.
2. Background Art
Tubular linear motors, or TLIM's, having a primary and a secondary, provide a means for linear propulsion. The secondary typically consists of a cylindrical body of ferromagnetic material having a surface covered by a layer of highly conductive material. The layer faces the primary, and is separated from the primary by an air gap.
The primary consists of a plurality of coils and thin ferromagnetic laminations. The laminations have a width and a length defined by a first and a second end. A series of notches are formed in the width of each lamination. When the laminations are aligned side by side, the notches collectively form channels which extend in a direction perpendicular to the length of the laminations. Each coil comprises a plurality of wires wrapped cylindrically into a disc shaped body having an inner and outer diameter. Each revolution of wire within the coil is referred to as a "winding". The windings of each coil begin with a first lead and end with a second lead, both of which extend outside of the coil for connection to other coils and or to the power source. The coils are received within the channels.
The laminations may be arranged in a number of different configurations. One configuration uses four separate groups of laminations symmetrically arranged around the coils and cylindrical secondary. The coils are received within the aligned channels of the lamination groups. A pair of annular flanges, one on each end of the laminations, hold the lamination groups and the coils together. The secondary is free to move axially within the center of the coils.
The number of coils in the primary is directly related to the number of poles in the motor and the number of phases present in the current passed through the coils. For example, if the current used is three phase alternating current (AC current) and the motor is a two pole motor, the motor will have six coils. By convention, when using three phase AC current, the three phases of the current are designated "U" "V" and "W". In the aforementioned example, therefore, the coil arrangement can be described as UVWUVW (The bars over the latter three coils by convention designate current traveling in a direction opposite that in the first three coils). In a four pole motor, for example, the coil arrangement would be UVWUVWUVWUVW, and so forth. A person of skill in the art will recognize that each phase of each pole may comprise more than one pole; i.e. UUVVWWUUVVWW describes a two pole, three phase AC current motor having two coils per phase, per pole.
It is known in the art that coil leads may be connected using connection plates that are bent in a complicated manner. There are several disadvantages to connecting coil leads in this conventional manner. One disadvantage is that the connection plate bending work must be done manually and even in the simplest of TLIM's, this task is time consuming and complicated. In TLIM's having a plurality of coils in each phase of each pole, the complexity of the task greatly increases and therefore becomes quite arduous.
Another disadvantage of the conventional method of connecting the coil leads is that both ends of the connection plates need to be soldered to the lead sections. The soldered connections require that solder be applied to the lead sections and to the connection plates beforehand. A large amount of time is, therefore, consumed preapplying solder and subsequently soldering the plates and the leads together. In addition, as the coil temperature increases when the linear motor is operated for a long time and the solder nears the melting point temperature, the strength at the connection may decrease.